Lesson 80

Area of a Rectangle

and a Square

By: Sir. Rei Marasigan

Alaminos District

Laguna

15X50=

500 X 20=

​

3000 ÷ 100=

1500 ÷ 100=

180 X 100=

500 ÷100=

Drill

Answer mentally.

120 X 20=

200 X 10=

200÷ 50=

750

2400

2,000

18,000

10,000

5

30

15

4

Review

Convert the following measurements to the indicated unit of measure:

a. 300 cm= ___m

b. 10m=_____ cm

c. 5 m = _____cm

d. 6 000cm = ____m

e. ¾ of 800 cm = ____m

​

3

1000

500

60

6

Motivation

1 cm

1 cm

What can you say about the illustration?

What does it show?

Developmental Activities

Presenting the Lesson

Identify the shapes given in our figure below.

square or

a rectangle.

One small square inside the square/rectangle is equal to 1 square unit.

The number of square units that covers the region/surface of the

rectangle/square is called its AREA.

What is the area of the figure below?

How did you get the area of each figure?

The column is referred to as length and the row is referred to as width.

Column

width

What is the relationship of the length and width to the area?

(the product of the length and width is equal to the area)

How can we get the area of a rectangle?

Area of a rectangle = length x width

A=lxw

• How can we get the area of a square?

Area of a square = side x side

A=sxs

• If the length of one small square is equal to 1 cm, what is the area of each figure?

Side

Side

A=3 X 3 = 9 sq.cm

Complete the table below.

Answer Key:

Performing the Activities

Groups 1 and 2

Materials: Activity sheet, tape measure, piece of cloth or Manila

paper (1 m by 2 m), notebook (15 cm by 20 cm),

ID card (8 cm by 12 cm)

Groups 3 and 4

Materials: Activity sheet, tape measure, plastic cover (75 cm by 75 cm),

part of the room (2 m by 2 m), handkerchief (42 cm by 42 cm)

Measure the length and the width of each object then fill in the table.

Processing the Activities

• Present your outputs. Discuss how you got the area of each object given.
• How do we get the area of a rectangular figure? How about the

area of a square figure?

Reinforcing the Concept

Answer the following problems.

1.Find the area of a square with side 15 cm. Write the solution or formula and then solve for the area.

Solution. A = s x s

A = 15 cm x 15 cm = 225 sq. cm

2. A rectangular garden has an area of 24 sq. m. If its length is 6 m, what is its width?

Given: A = 24 sq. mlength =6mwidth = ?

A=lxw

24 sq. m = 6 meters x width

Width = 24 sq. m ÷ 6 meters

Width = 4 meters

Summarizing the Lesson

How do we find the area of a rectangle?

In finding the area of a rectangle, use

Area = length X width or

Area = l x w

Applying to New and Other Situations

1) Ang area ng isang parihaba ay 180 sq. cm. Kung ang haba nito ay 15 cm, ano ang lapad nito?

​

2) Alin ang mas malaki ang area, parihaba na may habang 24 m at lapad na 6 m o parisukat na may gilid o side na 12 m? Ipaliwanag.

Evaluation

Sagutin ang sumusunod. Ipakita ang solusyon sa sagutang papel.

1) Hanapin ang area ng parihaba na may sukat na: Haba= 12 cm, lapad = 7 cm

2) Ang area ng silid ay 108 sq. m. Kung ang haba nito ay 12 metro, ano ang lapad nito?

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Home Activity

Pag-aralan ang floor plan na nasa ibaba. Hanapin ang area ng sumusunod:

1)Kusina (Kitchen)

2)Silid-kainan (Dining Room)

3)Silid ni Ana (Ana’s Bedroom)

4)Silid-tulugan (Master’s Bedroom)

5)Palikuran (Toilet)

6)Sala (Living Room)